铁电-宽禁带半导体薄膜的外延集成、界面极化耦合效应与高迁移率晶体管器件研究

The integration of ferroelectric film with wide band-gap semiconductor is the key technology for the future applications in power electronics and smart sensor systems. In this project, we propose to achieve the high-quality epitaxial integration of PMN-PT ferroelectric film with GaN-based wide band-gap semiconductor. The domain matching epitaxial mechanism of PMN-PT films on GaN and AlGaN/GaN epilayers will be intensively studied. The coupling effect between the ferroelectric polarization of PMN-PT and the piezoelectric polarization of AlGaN/GaN will be in-depth analyzed, which aims to realize the modulation of the two-dimensional electron gas (2DEG) at AlGaN/GaN interface through the ferroelectric field effect of PMN-PT film. The Metal-Ferroelectric-Semiconductor High Electron Mobility Transistors (MFSHEMT) will be further developed, which employs PMN-PT film as the ferroelectric gate and the AlGaN/GaN 2DEG as the channel. The ferroelectric polarization status in PMN-PT can be controlled by adjusting the structure and composition of the film, which can further modulate the 2DEG density and distribution in the AlGaN/GaN channel. The enhancement-mode MFSHEMT devices will be further demonstrated with controllable threshold voltage based on the ferroelectric-modulation of 2DEG channel. The proposed AlGaN/GaN based MFSHEMT device exhibits many advantages over the conventional HEMT, such as simple enhancement mode device structure, controllable threshold voltage, low gate leakage and nonvolatile behavior, which will be very promising to develop novel high frequency/high power semiconductor devices and multifunctional integrated smart sensor systems.

铁电薄膜与宽禁带半导体的集成是面向功率电子、智能传感等新兴高技术产业应用的关键技术。本项目拟在宽禁带GaN及AlGaN/GaN表面外延生长PMN-PT铁电薄膜，通过深入研究外延生长机理与界面晶格匹配机制，实现PMN-PT铁电薄膜与GaN基半导体之间的高质量外延集成。深入分析PMN-PT/AlGaN/GaN异质外延结构的界面极化耦合效应，阐明PMN-PT的铁电极化与AlGaN/GaN的压电极化之间的相互作用机制，揭示PMN-PT薄膜的铁电场效应对AlGaN/GaN界面二维电子气的调制机理。通过控制薄膜的铁电极化特性，实现对AlGaN/GaN界面二维电子气的精确调制，开发出阈值电压可控的增强型MFSHEMT器件。基于PMN-PT铁电场效应的增强型AlGaN/GaN HEMT器件阈值电压可控、栅极漏电流低及非易失存储等特性，对于开发下一代高频高功率半导体器件及智能多功能集成器件具有重要应用意义。

基于高性能铁电薄膜在GaN半导体上的外延设计，研究铁电极化与AlGaN/GaN异质结界面2DEG的耦合机理，探索铁电栅基增强型高电子迁移率晶体管对于开发高性能GaN基功率电子器件具有重要研究价值。在本研究中，采用缓冲层技术实现高性能铁电薄膜在GaN上高质量外延集成，以高质量FE/AlGaN/GaN铁电-半导体异质结为基础，通过调控铁电薄膜的极化状态实现了对于界面2DEG的完全耗尽，系统揭示铁电极化与界面2DEG的耦合机理，制备了铁电栅基HEMT器件。具体在材料设计、物理机制和器件研究方面的创新性结果如下：.(1) 系统揭示了钙钛矿型PMN-PT铁电薄膜在纤锌矿型GaN半导体上的外延生长规律及生长机理，基于界面缓冲层设计实现了高性能PMN-PT铁电薄膜在GaN上的外延集成。.(2) 基于晶格匹配的外延生长机制，通过界面晶格设计实现了钙钛矿型SrTiO3模板层在纤锌矿型GaN上的高质量外延集成并深入揭示了外延生长机理，以STO模板层为基础实现了高性能BaTiO3(BTO)铁电薄膜在GaN上的高质量外延集成。.(3) 基于所集成的BTO铁电栅层材料和界面晶格结构设计，构筑了高质量BTO/MgO/AlGaN/GaN/Si铁电-半导体异质结，系统揭示了BTO中铁电极化与AlGaN/GaN界面2DEG的耦合机理，实现了对于界面2DEG的完全耗尽，证明了铁电栅基增强型HEMT器件的可行性。.(4) 基于新型铁电栅层材料Hf0.5Zr0.5O2(HZO)及界面晶格设计，构筑了高性能HZO/MgO/AlGaN/GaN/Si外延异质结，通过改变HZO铁电极化状态实现了对于异质结阈值电压由-3.8 V到+3.2 V之间的可控调控，并探测到高达+5.5 V的阈值电压，以上述高性能异质结为基础制备了铁电栅基HEMT器件。. 综上所述，本研究对于开发高性能铁电栅基增强型HEMT器件及相关功能集成器件具有重要研究价值。基于上述研究，目前已发表16篇SCI论文，申请6项发明专利。